Dial-testing circuit



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April 12, 1927.

RQB. MILLER DIAL TESTING CIRCUILJ.`

iled June 30. 192e s sham-,sheet 2 y 1,624,422 April l2 1927 R. B. MILLER DIAL TE-STING CIRCUIT Filed June 50. 1926 3 Sheets-Sheet 5 Patented Apr. 12, 1927.

- warren :STATES P A'TEN T O FFII'CE.

ROBERT B. MLLER, OF JACKSON HEGHTS, NEW YORK, ASSIGNOR TO WESTERN ELEC- TRIO COMPANY, INCORPORATED, -OF NEW YORK, lN. Y., A CORPORATION OF NEW YORK.

DIAL-TESTING CIRCUIT.

Application filed; .Tune 30, 1926. Serial No. 119,529.

invention relates to Atelephone eX- systems and more particularly to equipment tor machine switching This change testing ltelephone systems.

'ztor informing the person 'making' the test ot' the resultot-such test.

Another 'feature ot this invention is thc provision ot means associated with a dial tester yto transmit distinctive signals indicaltive ot' vthe speed impulses yotl adial under test.

An additional featurei-s the provision of means associated with a dial tester under remote control to determine whether-the ftester shall vfunction Ito conduct any one of tour tests.

AY still further 'feature ot this invention is the provision ot means to enablea repeattest to befmade without lreestablishing the circuits to the dial tester.

` of switching` apparatusthe test operator connects the test cord lwith `the `substation at which the test man is working; The operator also operates a vcontrol key to indicate the, normal speed of the dial to be tested and the allowable variation in speed.

The dial test circuit automatically resets the dial tester pendulum and transmits al tone to ythe test'man. The test man ythen dials zero and a switch is stepped for each pulse. At the yirst pulse lthe dial tester pendulum is released and at 4the 'last pulse an indicator is tripped, operating a relay which completes atene circuit. A characteristie tone is provided itor tast. correct and slow ydial-s and the corresponding relay is ot a test cord `including the keys .for controlling the rdial tester and monitoring keys.

Fig. 2 shows a. switch for associating the dial tester with the test cord 4and other apparatus associated with the dial tester.

Fig'. 3 shows a switch for cont-rolling the application of the tests Vtogether with a pendulum type diaflftester.

The tester cord of Fig. 1 is a portion vof one disclosed and claimed in patent to E. R.

Lundius, No. 1,577,333, 1926.

The dial tester shown in the upper right hand -corner ot Fig. 3 claimed in the application of 1V. T. Booth and f1.0.. MagratlnSerial No.l 745,030, tiled October' 21, 1921i.

granted l\!laich 16,

Assuming that the dial l101 of the sub- A scribers set 100 is to be tested, the testing operator will be informed of the number of that subscribers line 'and she will, by means` ofthe plug 102 associated with ythetest cord 103, obtain connection 'with the subscribers 105 and 106 under the 'control of her sender 107. The insertion'ot plug 102 in jack .104A

visory relay 122 operates shunting` the lamp.

She will then operate dial testy key 108 and oneof thecontrol keys 111, 112, 113-01' 114, after which the operation will be automatic or under the control ot the test man at the subscriber-s station. The operation of a control key releases relay 122 and relights lamp 121.

The operation vot dial test key 108 will complete a circuit "trom battery through the winding ot' start rela-y 210, rightback vcontact -of relay 109, lower contact of key 108 to ground, starting` all idle dial testers hunting tor the cord 108. Theoperation of key is described and 'line 100 through a jack 104 and 'test selectors I 10S also connects battery through resistance 110, left hack contact of relay 109, inner lower Contact ot key 10S to the correspoml` ing terminal in the switches, such as switch 200, ol? all the dial tester circuits, marking the cord l'or selection.

lt also prepares a circuit from battery through the relay 100, middle lower Contact oil.t key 108 to the corresponding terminals in the are served hy brush 206 ot all, the dial tester switches 200.

The operation o1E relay 210 closes a circuit :troni ground at its right contact over Contact 211 o1 make-busy jack 2112,1'iglit hack contact ot relay 213, right hack contact of relay 21st right hack contact ol' relay 215. winding ot relay 210 to battery. Relay 2.10, in operating, closes' a circuit from battery through the winding stepping mag net 207, right lront contact ot relay 216 to the operating ground ot relay 210 over conductor 217. A circuit is also closed in parallel with relay 21.0 troni battery tln'ougl'i the winding ot relay 215 to ground on coiuluetor 217, hut relay 215 is preyented from operating hy a shunt around that relay at the hack contact oil' magnet 20T. lVhen magnet 20T is operated in the circuit previously traced, this shunt circuit is opened and relay 215 operates. Relay 215, in operating, opens the circuit of relay 216 which` in releasing', opens the circuit oit magnet 20T,` permitting that magnet to retract its armature and advance switch 200 to its next terminals. This operation is repeated until brush 205 makes contact with the terminal connected to hattery through key 108. lVhen this occurs, a circuit is completed from battery as preyiously traced over brush 205, Contact 218 of jack 212, left hack contact of relay 219, winding ot relay 213, windings ot relay 220, lett AFront Contact of relay 210 to ground. Relay 220 operates and closes a shunt around its right hand high resistance Winding, permitting the operation of marginal relay 213. The operation of relay 213 opene the circuit. ol relays 216 and 215 and ot magnet 207Y sothat siyitclr200 comes to rest in connection with cord 103.

The operation ot relay 213 closes a circuit from hattery through the winding of: relay 221. left hack contact ot relay 222, front contact ot relay 213, contact 211 of jack 212. right front Contact ot relay 21,0 to ground. Relay 221 operates and closes an ohyious operating circuit :tor relay 214.. Relay 2141. in operating. closes a circuit from hattcry through the Winding ot relay 109.` middle lower contact of key 10S, hrm-'h 200. right `liront contact ot relay 2111;. Winding ot relay 2221 to ground. Relays 109 aud 22? operate in this circuit'. The operation oi relay 100 removes hattery troni the terminal of brush 205. thus releasing relays 21E-l and 220. It also opens` the circuit ot relay 210 bringing the reniaining dial test circuit switches to rest. The operation oit relay 223 closes a holding circuit` tor relay 21e which does not release prematurely since relay 221 is slow to release. llelay 22? also closes an obvious energizing circuit for relay 230 which relay closes a portion o't an all circuits busy a1.'- rangement.

llhe apparatus is arranged to test either high speed or low speed dials and to impose either test or readiust speed limits upon the. dial. Distinction hetu'een these conditions is brought about hy the operation of one oi. the keys 111, 112, 113 or 1111 in the test cord. (flue ot these teys is operated for each (est. lley 1111 is operated to test a low speed dial at rcadjust limits; key 113 for a low speed dial at toet limits; key 112 for a high speed dial at readjust limits; and key 111 'to a high speed dial at test limits. The ogicration ot either key 112 or 114 connects hatter): oycrconductor 115, hrush 204, left trout contact ot relay 223, inner right armature oi" relay 221, through the Winding of either relay 310 or relay 346 to ground, rearranging` the segments otare 335 o1E the dial tester to .set readiust limits. lith either key 111 or 112 operated, ground is connected to conductor 116 and over brush 20S-l, inner lett liront contact o1 relay 214 to the winding of relay 22st, which rearranges the segments ot are to indicate correctly in testing a high speed dial. Assuming that the dial- 101 a low speed dial, as suliscrihers dials usually are, and that it is to he tested under readjust limits, key 1111 will he operated, thus extending the tip and ring conductors from the subscrihers line through the lnfushes 201 and 202 respectively. Then key 111 is operated, a circuit is closed from ground over its upiiermost Contact to the Winding ot relay 117, closing a monitoring circuit to the test operators headset. Another circuit Will he closed from battery through the right Winding of relay 311, middle leit't front contact of relay 251-1-, lnfush 202, inner lou'er operated contact ot key 11d, inner lower normal contacts ot keys 113, 112, 111 and 11S. ring of plug 102 and jack 104, thence oycr the suliscrilwi"s loop through dial 101 hack to the tip ofi jack 101 and plug 102. upper middle normal contacts ot keys 110. 111, 112, and 1123, inner upper operated contact olI key 114 brush 201 outer lett contact ot relay 21-l left winding of relay 225 to ground. Relay 31.1. in operating closes a circuit trom battery over ital right iront contact. normal contact ot brush 5301, left hack contact' ot relay 312. hack contact o1 stepping nnignet 312. winding of relay 214 to ground. llclay 314. in operating. closes a circuit trom hatlery over its right Front contact. winding oi 'relay :115, winding of inaguct 11121 to ground. hiagnet 313 operates. opening the circuit of: relay 314, which in lili-J Gli proper centering ot trip arm turn-opens the circuitk of fthe magnet and kthus steps switch 30010 `position `1. Relay 315 operates but r`performs no useful function at @this t-ime.

v In position 1, acircuit i-sfclosed` Eft'ron'i'loattery over brush304 to battery li'eed conductor'316. A circuit is completed from conductor '316 over brush 303, left winding of 1ela1y'317 to ground. A circuit is also completed from conductor l3:16 to ground through the windingof relay .222. Relay 317 yin operating locks over .its inner lett contact to conductor 316 fthrough the inner right .normal contact ot yrelay 318. It also closes -a lcircuit from 'battery foyer 'the front contact of relay 3'11, resi-stance 319, right front contact vand' right winding of Erelay 317, contact 320 ot 'key 347, Ito ground through the winding of holding magnet 321. It also closesy an `obvious energizing circuit for relay 322. Relay 322 in operating prepares a- Ivlocking circuit tor itself which will be traced when completed.l It also connectsl a :substitute battery to cend'uctor316. It also completesa circuit from battery over its outer right vfront contact, No. 1 terminal otbrush 301-, lett back contact yo't`-relay 312, back Contact of magnet 313 fto v'the `winding of relay 314. As previously described, rela-y 3f14-canses switch 300 to ladvance `-to its next terminals.

'Vith switch 300 in position .2', a circuit is closed -from lground 'through the windingof relay '323, -'N0. l2 :terminal ot' brush 303 to battery on-conductor'316. The operation of relay 323 closes a circuit'from battery over the trontcontact ot relay 323 to the lwinding of reset solenoid The operation i of "this solenoid moves lreset arm'350 to the left extremityof its swing.y Arm 350 mechanica'lly engages pendu-lumv -3'51 and trip larm` 352. W'hen pendulum 351 reaches v'its extreme position it comes under the control of the holding magnet 321 Where `it will 'be held independent of arm 350. Arm 350 in this' position closes contact 325., eompletinga circuit from ground over vContact 325 'through the right yWinding of relay 326, No. '2' terminal ot arc 304 -to battery over conductor 316. The operation oit/relay 326 closes a circuit frombattery -to the No. v2"terminal of arc 301, completing the previously traced circuit for r-elay'314, and advances switch'300 to position'3. For a complete description ot vthe operation and `relative `positions of the parts ot the dial'tester pendulum, reference is made to the above identified Bootl1`\lagiath appli;

cation.

ii'th .switch I300 in Aposition '3, battery is removed trom relay 326 and'that relay releases. "However, the circuit of magnet 324 is maintained at this time to insure the circuit is completed at this-.time .from vground through the llett winding of relay 327, No. '3 terminal 'of arc 304 to battery over conductor 316.y Relay 327, yin operating, closes a locking circuit lfor :itself from .battery on conductor '316, back contact Kof relay 328, resistance 329, righ-t front contact and right winding of relay 327, Contact 330 of liey 347, Winding of trip magnet to ground'. vThe energization of magnet 33.1 holds the trip arin 352: in proper 7 relation to the pendulum '351. rhe operation Vot relay also closes=a circuitftrom battery at the outer 'right iront contact olf relay 322, inner right Contact of relay '327 to No. 3 terminal of arc V30-1, advancing switch 300 to position 4.

hile switch 300 passes `from :position to position 4, battery is removed from thel lett winding of relay 327 so that relay 327 remains energized in series With'tri-p magnet 331 atthis Stime. Battery is removed vvtrom-r the winding ot solenoid 3241aiidt-liereset arm '350 is allowed to .swing Ainto its position at the rright of the arc where it remains. This prevents it from interfering with the tree swing of pendulum 351. lVhen it reaches its extreme lright position, a circuit is closed from ground over contact '332, left windingl of relay 326, No. 4* terminal olt arc 304 to 'battery on conductor 316. Relay 326, in operating, connects vbattery 'as before to are '30-"1 and advances switch`300 to position 5A lVhile switch 300 vmoves 'from position 4 to position 5, 'relay 326` is released. A circuit is now completed from battery' Yover the outer right front contact of relay `31.7, No. '5 terminal of arc'302, winding ot' frelay 318 to ground causing irelay 3'18 yto operate. The operation. of relay 313vcloses v-a circuit from conductor '316 over the outer right front contact ot relay 3218, wind'ing'ot relay 312 to grou-nd. Relay `313 also .removes battery from one `locking circuit ot relay 3-17 but relay 317 is 'held 'operated in series with magnet 321.y It completes 'the lo'cliing circuit of relay 322 `which .may A.be traced from battery on conductor 316, inner right front Contact of relay 318, inner left front Contact and left Winding otlv relay '322 to ground.

The operation of relay 312 arranges the circuit of relay 314 to make it function as a pulse helping relay in the subsequent test. It also extends the circuit of lmagnet 313 to the back Contact of relay 311. V'hil'e switch 300 was in position 4, a circuit was closed from groundftl'irough the winding' o;t` relay 219, No. 4 terminal of brush 303 to battery on conductor '316. Relay 219 operated and locked to battery at the -front contact ot relay 311. Relay 211.9 also completed a circuit `from .battery through resistance 226, lc'lf't lront conta-.ct of :relay 219, contact '.313 oi jack-"91" brush-205, inner elower con-- may "Winding ot relay 31S to ground. Relay a tact ot key 10S, lett front contact of relay 109, winding ot relay 119 to ground. The operation oi relay 119 completes a monitoring circuit for the test operator. A circuit `is now completed l'rom ground, through tone source E227, right. baci; contact o1 relays 22S, i229 and 280, right winding o1 relay 225, No. terminal ol arc 301 to battery7 on conductor 31.6. AA tone is induced in the Vlett winding oit relay and thence over 'Jill will cle-energize magnet 321 and relay 31K permitting the pendulum to swing frcely. then relay 311 closes its Mick-contact, a circuit is closed 4from battery over the baci: contact ot' relay e1111 back contact ott rela)1 333, t'ront contact of relay 312. Winding o'l.E relay 315, Winding of magnet S13 to ground. A parallel circuit also completed lroiu the right front contact oi.E relay Sli over the lett front contact oi? that relay. back contact of the magnet 313, winding o1 relay 311 to ground. Relay 3141 when operating connects battery over its right lront contact to the windings olI relay 315 and magneAv 31?). thus insuring that magnet 313 will conu'iletely attract its armatures and step switch 300 in response to each release of relay 311. Relay 318 is operated ink positions l to 15 in a circuit from battery over the front contact ot relay 225, strapped terminals ot are 302.

295 releases at cach dial pulse but relay 314 closes a substitute circuit for relay 318 extending from battery; inner right lront contacts of relays 322 and 318. left contact ot relay 314 to the Winding ot relay 31S. Relay 318 is slow to release to insure that it will be held operated in spite of the interruptions ot its circuit.

In response to the interruptions ot the circuit of relay 311 by the dial 101, switch. 5100 will be stepped to position 15. lVhen brush l0-l reaches position 1st. a circuit .is closed from battery on conductor 5311i` brush $304. winding ot relay Sile. outer lett l'ront contact ot .relay 322 to ground. Relay $35311 operates and closes a locking circuit for itselfthrough the Winding ot relay 329 to battery at its inner right iront contact. Relay is prevented from operating at this time by the battery on brush 301. The operation oi` relay 33t also closes a second holding circuit tor trip magnet 831 orer its t ront coutact to battery at the right front contact ot relay` B11. lllheu switch 300 steps into position from position lll, the shunt is removed from relay 328 and that relay operates, relay 311 being operated at this time. Magnet 331 is held operated at the front contact of relay 311. lVhen relay 311 releases tor the tenth pulse, relay 32T and trip magnet 331 will release. The release ol relay 327 prevents the reclosure ol the circuit olf trip magnet 33 The release of trip magnet 3231 permits the trip arm to come in contact with one oit the commutator segments of strip 335. The trip arm remains in trictional contact with the conunutator segment to indicate the distance traversed by the pendulum during the time that the dial sent ont ten pulses. Assuming that the trip arm made contact with segment 340, a circuit is closed from ground over the trip arln S52, segnient 340. lett back contact ot relay 224, winding of relay 230 to battery on conductor 316. Relay 230 operates and closes a circuit ;troin tone source 22T tlirough high speed interruptor Q31, left lront contact ot relay 2-l0, right winding o't relay No. 15 tcr minal ot arc ltll to battery on coluluctor 316. lfhis tone will be induced. in the sulfiscribefs dial circuit. and will be received hy the test man at the substation. This tone indicates that the dial is too tast.y since the pendulum had not swung tar enough before the completion ot the ten pulses.

Relay 219 was released, and the monitoringr circuit opened during dialing` but at the completion of dialing;l a circuit is reestablished for relay 219 and the monitoring circuit is again completed. The test operator will therefore also hear the tone. This also atliords an opportunity for the testinan to instruct the test operator tor any purpose.

Had the trip arm 352 been released to malte contact with either segment- 837, 338 or 339 a circuit would have been closed from batteri ou conductor 316 through the Winding of OK relay 22.1% right back contact ol relay 92a to segment 33S or over a back contact of relay 310 to segment 337 or 339 and thence through the trip arm 352 to ground. The operation oit relay "229 connects ringing current trom source 232 over its `front contact to the right winding of relay 225 thus producing ringing current tone in the receiver at the suhscrihei"s substation and indicating to the testman that pulsing has been at the right speed. lt the trip arm is released to make contact with segment 336, a circuit is closed trom battery on conductor 316 through the winding ot relay 228 segment 3BG. trip arm 352 to ground. The operation of relay Q28 completes a circuit from tone source 227 through slow interruptor 233, trout contact ot relay 228 to the right Winding ot .relay 9.27 producing a slowly interrupted tone in the substation receiver to indicate that pulsing was too slow.

lt' the dial has proved too slow or too tast, the test man may repeat the test after lll) adjustment by restoring the receiver ,at the substation to the sw-itchhook i'or a moment. The restoration of. the, receiver opens the circuit'ofrelays 225 and 311,.causing these relays to reiease. The release ofV relay Y225 opens a circuit of relay 318 which in turn opens the circuit ot relays 322 and 312. The release of relay 312 turns the operating circuit for magnet 313 to the control of relay 314. A circuit for operating relay 314 may be traced from battery at the right back Contact oi relay 322, right back contact of relay 312, strapped terminals of arc 301, lett back contact or' relay 312, back contact ot magnet 313, winding otrelay 314 to ground. Relay 314 operated steps switch 300 to position 16. r1`hek above traced circuit for niagnet 313 is reclosed in position 16 and the switch stepped in this manner to its normal position. lVith switch 300 inv position 16 relay 345 is operated in la' Circuit from ground through the winding lof relay 345, No. 16 terminal of brushes 304 andy 303 to battery. Relay 345 locks' over its inner right cont-act, right :front contact of relay 315 to battery at the outer right Contact oi'` relay l345. Relay 315 is held operated during they advance ot switch 300 to normal by its slow to release character. TvVhen switch 300 reaches normal the circuit of relay-315 is permanently opened and relayl 345 releases.. 'Relay 345 whileoperated extends battery from its outer right front contact to conductor 316 in substitution for the battery removed therefrom by the release of relafy 322. This servesto hold relay 222 operated. lVith switch 300 normal and. relay 340 released, the holding circuit yof relay 222 is opened and thatrelay releases. With relay 222 released. the holding circuit ot relay ,214 is dependent entirely upon relay 223, which it will be remembered is held operated through key 103 and relay To repeat the test the test man againremoves the receiver at the substation 100 from the hook, reoperating relays 311 and k225. rLhe operation yof relay 311 causesthe ad.- vance of switch 300 in the manner previously described and the test may berepeated.

It itis desired to test ythe dial at substation 100 under readjust limits,.the key 113 may be restored and key 114 operated. whereupon theconditionset up will be that of the reyadjust standards. Aspreviously stated, the operation. of key 114 closes a circuit for opera-ting yeither relay 310 or relay 346 according to the speed of dial under test. Inthe present case, relay 310 would be operated andlwould. lock over the back Contact of relay 346 and back contact oi relay 345 to 'battery on. conductor 316. The operation or relay 310 regroups the segments ot strips 335.

Inforder` to use thesame apparatus for testing a highspeed dial, as previously indicated relay ',224. readjusts lthe segment arlforth.

rangement so as to test. dials which normally pulse at the .rate of. 20 pulses per second. Relay 346 perforinsthe same functions for a high speedV diali as relay 310 does for a low speed dial. The 'following table sets toi-.th indication giveninider the various test conditions.

Fast. OK. Slow.

Relay 224, nor- Relay 310, normal 3 4 0 t o 3 3 7 t o 336 mal (1l) pulsov (test limits). 344y 339 dial).

ARelay 310, oper- 3 3 9 to 33S 336,337

ated (readjust 344A limits).

Relay 224, op- Relay 346, normal 344 3 4 l t o 3 3 6 t o crate d (20 (test limits). v 343 340 pulse dial).

f Relay 346, oper- 343,344 342 3 3 G t o ated (readjust 341 limits).

ytrip a'rm to engage segment 336.

1n order to disconnect, it isA necessary that key 108 be restored. The restoration or" thiskey opens the circuit of relay 109 and relay 223 thus releasing the apparatus completely and restoring it. to normal. It' the dial test circuit is selected and the testl abandoned without operating one or' the keys 111 to `11.4,no circuit will have been completed for relay 311 andi switch 300 will nothave been. -moved oinormal. Hence the restoration of dial test. key 108releases the circuit immediately. If one of the test keys 111 to 1.14 has been operated so that switch 3001has been moved o normal in a mannerpreviously described, the advance of the switch to position will be as above set The restoration of the test key or of' the subscribers receiver releases relay 311 and with switch 300 in. position 5 and I relay 311 de-energized a' circuit may be traced from battery at the back contact of relay 311 over the back contact of relay 333, liront contact of relay 312, winding of relay 315, winding of magnet 313 to ground, stepping: switch 300 to terminal 6. Vilith relay 311 released the locking circuit of relay 317 to the holding magnet` 321 is open and that relay isreleased. The release of relay 317 opens the circuit ofl relay 318 and that relay also releases, in. turn: releasing relays 322 and. 312. The release or relay 322 closes battery over its outer right back contact, back contact of relay 312, strapped Aterminals of arc 301,. left' back contact of relay 312 `back contact. of magnet 313,.Winding of relay 314 to y ground4 restoring' switch. 300- to lll] l'il) lil) normal. Relays and 2l-1l are held operated until, the switch reaches normal in the manner previously described.

'.lhc circuit is provided with a. maltebusy jack The insert-ion ol' a plug in this jacl; opens thc circuit oil relays 2113 and 2:10 preventing any line on lwhich switch 2d() might be resting from being made busy. it also opens the circuit for controlling magnet T preventing the switch 200 from moving in a hunt-ing operation. lt also opens the circuit ot relay i214; preventing the closure ol' the conductors from the test cord, and thus preventii'ig interference with any test cord on the terminals ot which switch 200 might be standing. ln addition itcloses a ,link in a chain circuit through the dial tester circuits which operates relay 22A and lights lamps 235 when all the dial tester circuits are busy.

Keys SLi-T and 3118 are provided to permit checking the calibration ot' the pendulum whenever desirable. The tester circuit is made busy as above described. The ope rtion ci key Seli closes a circuit from ground over the contact 3&9 through the winding ot rclaylll operating that relay. rlhe operar lion of relay 311 causes the stepping or switch 300 in the manner previously described. Relay 317 is operated and locked as before except that the locking circuit is transferred to the control olI key 3&8 by the operation ot hey Si?. rlhe circuit ot relay im" and its locking circuit through the trip nuignet 331 also closed, holding the trip arm ont ot the path ont the pendulum. When the pendulum is set, the operation ot' hey 5i-,S releases the pendulum and permits it to oscillate freely. A Window in the case ol thc pendulum permits observation or' the `movement and the rate ot vibration may be determined in any well known manner. Atter the ehecl; has been completed the restoration oi" keys 34S and 3ft? permits the restoration ot this circuit to normal and the removal oi the plug from jack 212 renders the circuit available for testing purposes.

What claimed is:

l. In a telephone exchange system, an opcratoi"s position, a test circuit available to sa id position, a telephone circuit, an impulse transmitter associated therewith, means at said position lor connecting said test circuit with` said telephone circuit, means `i n said test circuit controllable over said telephone circuit to determine the speed ot' pulsing by said transmitter, and `means to transn'iit a signal to said telephone circuit to indicate said speed.

ln a telephone exchange system, an operatoris position, a test circuit available to said po` tion, a telephone circuit, an impulse transmitter associated therewith, means at said position for connecting said test circuit with said telephone circuit, means in said [est circuit cmitrollalile over saidtelephone circuit to determine the relative speed ol pulsing by said transmitter, and means to transmit a characteristic tone to iiulicate said relative speed.

3.111 a telephone exchange system, an opcrators position, a test circuit available to said position, telephone circuits, impulse transmitters associated with said circuits, said transmitters having dilliercnt normal pulsing rates, means at said position ior connecting` said test circuit with a telephone circuit, means in said test circuit controllable over said telephone circuit to determine the relative speed otpulsing by the transmitter associated with said telephone circuit, and, means controllable from said position to arrange said test circuit to itunetion at (he normal pulsing rate oli' thc transmitter under test.

4.111 a telephone exchange system, an operator-ls position, a test circuit available to said position, a telephone circuit, an impulse transmitter associated therewith, means at said position 'loi" connecting said test circuit with said telephone circuit, means in said test circuit controllable over said telephone circuit to determine the relative speed ot' pulsing by said transmitter, means to transmit a characteristic signal to indicate whether the speed of pulsing is satisfactory', and means to vary the range oil speeds which shall be satisfactory.

5. in a telephone exchange system, a plurality oit' test operators7 positions, a test circuit common to said test positions, a telen phone circuit, an impulse transmitter associated therewith, means at each oi said positions lior connecting said test circuit with said telephone circuit, means in said test circuiteontrollable over said telephone circuit to determine the relative speed of pulsing by said transmitter," and means to transmit a signal over said telephone circuit to indicate said relative speed.

(l. In a telephone exchange system, a piurality of test operators positions, a test circuit common to said test positions, a tele phone circuit, an impulse transmitter associated therewith, means at each `of said post tions l'or connecting-said test circuit with said telephone circuit, means in said test circuit controllable over .said telephone circuit to determine the relative speed of pulsing by said transn'iitter, and means to transmit a characteristic tone to indicate said relative speed.

7. In a telephone exchange system, a plurality of test operators positions, a test circuit connnon to said test positions, telephone circuits, impulse transmitters associated with said circuits, said transmitters having different normal pulsing rates, means atcaeh ot said positions for connecting said test cir cuit with a telephone circuit, means in said 'Lest circuit controllable over said telephone circuit to determine the relativ-e speed of pulsing by the transmitter associated with said telephone circuit, and means eontrollable trom said position to arrange said test circuit to function at the normal pulsing rate ot the transmitter under test.

8. In a telephone exchange system, a plurality of test operators positions, a test circuit common to said test positions, a telephone circuit, an impulse transmitter associated therewith, means at each of said positions lior connecting said test circuit With said telephone circuit, means in said test cir cuit controllable over said telephone circuit to determine the relative speed of pulsing by said transmitter,v means to transmit a characteristic signal to indicate to said telephone circuit whether the speed oi pulsing is .satisfactory or unsatisfactory, and means to Vary the range of speeds which shall be satisfactory.

9. In a telephone exchange system, a plurality of test operators positions, a test circuit common to said test positions, a telephone circuit, an impulse transmitter associated therewith, means at each ot said positions for associating said test circuit with said telephone circuit, means in said test circuit controllable over saidtelephone circuit to determine the relativ-e speed ot pulsing by said transmitter, and means to repeat saidV test Without reestablishing the circuits connecting said impulse transmitter with said test circuit.

l0. In a telephone exchange system, a purality ot test operators positions, a dial test circuit common to said test positions, a subscribers substation, a dial thereat, means .at each of said positions for associating said dial test circuit with said substation, means in said dial test circuit controllable from said substation to determine the relative speed of pulsing by said dial and means to transmit a tone of one character to indicate that the speed oit said pulsing is correct and to trans- .mit .a tone of one character to indicate that the speed of said pulsing is correct, to trans- --mit a tone oit a different character to indicate that the speed ot said pulsing is mcorrect and means to interrupt said latter tone at di ii'erent rates to diiierentiate pulsing which is too fast :trom pulsing` which is too slow. i

12. In a telephone exchange system, a piurality ot test operators positions, a dial testJ circuit common to said test positions, a subscribers substation, a dial thereat, means at each ot saidpositions tor associating said dial test circuit with said substation, means in said dial test circuit controllable from said substation to determine the relative speed ot' pulsing'` by said dial and means to retest said dial under the same ordiiterent conditions without r-eassociating said dial testset Wit-h said dial. i

18. In a telephone exchange system, a plurality ot test operators position, a dial test circuit common to said test positions, a subscribers substation., a dial thereat, means at each ot' said positions 'tor associating said dial test circuit with said substation and gtor determining the test conditions to be imposed, means in said dial test circuit controllable trom said substation to determine the relative speed ot pulsing by said dial and means to transmit a signal to said substation to indicate said relative speed.

In Witness whereof, I hereunto subscribe my name this 25th day of June A. D., 1926.

ROBERT B. MILLER. 

